Numerical Modeling of Formation and Rise of Gas and Dust Cloud from Large Scale Commercial Blasting

Abstract

The emission of dust particles into the atmosphere during rock mass breaking by blasting in ore mining open-pits is one of the factors that determine the ground-level air pollution in the vicinity of pits. The data on dust concentration in the cloud, which is extremely difficult to obtain experimentally for large-scale explosions, is required to calculate the dust dispersion in the wind stream. We have elaborated a Eulerian model to simulate the initial stage of dust cloud formation and rising, and a Navier–Stokes model to simulate thermal rising and mixing with the ambient air. The first model is used to describe the dust cloud formation after a 500 t TNT (Trinitrotoluene equivalent) explosion. The second model based on the Large Eddy Simulation (LES) method is used to predict the height of cloud rising, its mass, and the evolution of dust particles size distribution for explosions of 1–1000 t TNT. It was found that the value of the turbulent eddy viscosity coefficient (Smagorinsky coefficient) depends on both the charge mass and the spatial resolution (grid cell size). The values of the Smagorinsky coefficient were found for charges with a mass of 1–1000 t using a specific grid.

Keywords

• atmospheric pollution
• numerical simulation
• commercial blasting
• gas and dust cloud
• turbulent mixing
• Smagorinsky coefficient